Hives

Also known as urticaria, hives are raised, itchy weals that appear on your skin. They can pop up anywhere on your body, vary from a few millimetres to the size of a hand, and may go away within a few hours or last for a few weeks.

Hives are a reaction to histamine, a chemical released by your body as part of the immune response.

They’re more common in children, women aged 30 to 60 and anyone who’s susceptible to allergies.

Hives are classed as either:

• Acute – when they last for fewer than six weeks
• Chronic – when they last for longer than six weeks

You may have:

• Raised, round or oval-shaped weals
• Red or flesh-coloured weals
• Itching, burning or stinging

Hives are usually harmless but sometimes they can be the first symptom of anaphylaxis, a potentially life-threatening allergic reaction. Other symptoms of anaphylaxis include:

• Swollen eyelids, lips, hands and feet
• Wheezing and breathing difficulties
• Feeling faint
• Tummy pain, nausea and vomiting
• Collapse and loss of consciousness

Call 999 if you think you or someone else has anaphylaxis.

Hives will probably go within 48 hours. But see your GP if they’re:

• Severe
• Causing distress
• Accompanied by other symptoms

Your GP will examine your rash and ask about other symptoms to help work out what’s causing it.

Acute hives

Tests are often not necessary but sometimes your GP may refer you to an allergy clinic.

Chronic hives

You may be referred for the following tests:

• Blood tests for thyroid conditions, immune system disorders and liver function
• A stool sample to detect parasites in your intestines

Acute hives

The most common cause of hives is an allergy. Common allergy triggers for hives include:

• Foods such as peanuts, shellfish, eggs and cheese
• Pollen
• Dust mites, insect bites and stings
• Pet dander (skin)
• Latex
• Chemicals
• Medication such as antibiotics, aspirin or non-steroidal anti-inflammatory drugs like ibuprofen

Non-allergy triggers include:

• Viral infections
• Emotional stress
• Physical triggers such as skin pressure, temperature changes, friction and even the sun and water

Chronic hives

Possible causes include:

• An autoimmune disease, when your immune system attacks its own body
• Viral hepatitis (liver disease)
• Underactive or overactive thyroid gland
• Parasites in your intestines

You may find that these triggers make hives worse or come back:

• Stress
• Alcohol
• Caffeine
• Certain medications
• Certain food additives
• Physical triggers

You may not need any treatment because hives often clear up within a couple of days. In the meantime, it’s best if you avoid any triggers you know you have.

Treatments include:

• Antihistamines, medicines which block the effects of histamine, the chemical that causes the weals and itching
• Menthol cream to soothe itching
• Short course of corticosteroids, which suppress your immune system

If you have chronic hives your doctor may also refer you to a dermatologist, a consultant specialising in skin conditions. They may suggest stronger antihistamines or other medicines to suppress your immune system, such as ciclosporin and omalizumab.